Endovascular device engagement

ABSTRACT

A medical device, configured to perform an endovascular therapy, e.g., thrombectomy, can comprise an elongate manipulation member and an intervention member. The intervention member can comprise a proximal end portion and a mesh. The proximal end portion can be coupled with the distal end portion of the elongate manipulation member. The mesh can have a plurality of cells and, be compressible to a collapsed configuration for delivery to an endovascular treatment site through a catheter, and be self-expandable from the collapsed configuration to an expanded configuration. At least a portion of the mesh, from a first location to a second location along the mesh, can be configured such that an amount of cell deformation in response to longitudinally directed tensile forces decreases by less than 5% or increases in a distal direction along the portion of the mesh.

BACKGROUND

Blood vessels can become occluded by emboli, e.g., thrombi. For example,intracranial arteries can become occluded by thromboembolisms.Disruption of blood flow by the occlusion can prevent oxygen andnutrients from being delivered to tissues downstream of the occlusion.Deprivation of oxygen and nutrients to tissue distal to an occlusion canimpair proper function of the tissue, and may result in cellular death.Cellular death increases with duration of the occlusion.

SUMMARY

An aspect of at least some of the embodiments disclosed herein involvesthe recognition that the location and longitudinal extent of thrombusengagement by a mechanical thrombus-retrieval device can affect thelikelihood of successfully capturing the engaged thrombus, and that thelikelihood of successful thrombus capture and retrieval can be improvedby increasing a longitudinal extent of substantially even thrombusengagement, distally shifting the region of thrombus engagement, orboth. When a thrombus is primarily engaged along a portion of thethrombus near its proximal end, and particularly when a longitudinalextent of substantially even thrombus engagement is small, the thrombusmay be more likely to fragment, become released from the retrievaldevice, or both.

The subject technology is illustrated, for example, according to variousaspects described below. Various examples of aspects of the subjecttechnology are described as numbered clauses (1, 2, 3, etc.) forconvenience. These are provided as examples and do not limit the subjecttechnology. It is noted that any of the dependent clauses may becombined in any combination, and placed into a respective independentclause, e.g., clause 1, 8, 22, 32, 40, 47, 56, 65, or 69. The otherclauses can be presented in a similar manner.

1. A medical device configured to perform an endovascular therapy, thedevice comprising:

-   -   an elongate manipulation member comprising a distal end portion;        and    -   an intervention member comprising a proximal end portion and a        mesh, the proximal end portion being coupled with the distal end        portion of the elongate manipulation member, the mesh having a        proximal mesh end, a distal mesh end, and a mesh length from the        proximal end to the distal end, the mesh having a plurality of        cells and being compressible to a collapsed configuration for        delivery to an endovascular treatment site through a catheter        and being self-expandable from the collapsed configuration to an        expanded configuration, and wherein at least a portion of the        mesh, from a first location to a second location along the mesh,        is configured such that an amount of cell deformation in        response to longitudinally directed tensile forces decreases by        less than 5% or increases in a distal direction along the        portion of the mesh, the first and second locations being        longitudinally separated by a distance that is more than half of        the mesh length.

2. The medical device of Clause 1, wherein the portion of the mesh, fromthe first location to the second location along the mesh, is configuredsuch that the amount of cell deformation in response to longitudinallydirected tensile forces does not decrease in a distal direction alongthe portion of the mesh.

3. The medical device of Clause 1, wherein the portion of the mesh, fromthe first location to the second location along the mesh, is configuredsuch that the amount of cell deformation in response to longitudinallydirected tensile forces increases in a distal direction along theportion of the mesh.

4. The medical device of Clause 1, wherein the first and secondlocations are longitudinally separated by a distance that is at leasttwo thirds of the mesh length.

5. The medical device of Clause 1, wherein the first and secondlocations are longitudinally separated by a distance that is at leastthree quarters of the mesh length.

6. The medical device of Clause 1, wherein the first and secondlocations are longitudinally separated by a distance that is at least90% of the mesh length.

7. The medical device of Clause 1, wherein the mesh is generallycylindrical in the absence of external forces.

8. A medical device configured to perform an endovascular therapy, thedevice comprising:

-   -   an elongate manipulation member comprising a distal end portion;        and    -   an intervention member comprising a proximal end portion and a        plurality of cells forming a mesh, the proximal end portion        being coupled with the distal end portion of the elongate        manipulation member, the mesh having a proximal mesh end, a        distal mesh end, and a mesh length from the proximal end to the        distal end, the mesh being compressible to a collapsed        configuration for delivery to an endovascular treatment site        through a catheter and being self-expandable from the collapsed        configuration to an expanded configuration, and wherein, from a        first location to a second location along the mesh, each cell        distally adjacent to another cell, in a longitudinal row of        cells, has a larger interior bounded area than has the another        cell, the first and second locations being longitudinally        separated by a distance that is more than half of the mesh        length.

9. The medical device of Clause 8, wherein the first and secondlocations are longitudinally separated by a distance that is at leasttwo thirds of the mesh length.

10. The medical device of Clause 8, wherein the first and secondlocations are longitudinally separated by a distance that is at leastthree quarters of the mesh length.

11. The medical device of Clause 8, wherein the first and secondlocations are longitudinally separated by a distance that is at least90% of the mesh length.

12. The medical device of Clause 8, wherein the longitudinal row ofcells comprises at least three cells.

13. The medical device of Clause 8, wherein the first location is at theproximal mesh end.

14. The medical device of Clause 8, wherein the first location is distalto a proximal-most cell.

15. The medical device of Clause 8, wherein the second location is atthe distal mesh end.

16. The medical device of Clause 8, wherein the mesh is cylindrical inthe absence of external forces.

17. The medical device of Clause 8, wherein the elongate manipulationmember has a length between a proximal end and the distal end that issufficient to permit manipulation of the intervention member within thecerebral vasculature of a patient's body from a location outside thebody.

18. The medical device of Clause 8, wherein the mesh is formed by lasercutting one of a tube or a sheet.

19. The medical device of Clause 8, wherein the mesh forms a generallytubular structure.

20. The medical device of Clause 8, wherein the mesh further comprises afirst lateral edge extending between the proximal mesh end and thedistal mesh end, and a second lateral edge opposite the first lateraledge, the second lateral edge extending between the proximal mesh endand the distal mesh end; wherein the first and second lateral edges areoverlapped in a coiled configuration about the longitudinal axis whenthe mesh is in the collapsed configuration.

21. The medical device of Clause 8, wherein the tube has an openproximal end and an open distal end.

22. A medical device configured to perform an endovascular therapy, thedevice comprising:

-   -   an elongate manipulation member comprising a distal end portion;        and    -   an intervention member comprising a proximal end portion and a        plurality of cells forming a mesh, the proximal end portion        being coupled with the distal end portion of the elongate        manipulation member, the mesh having a proximal mesh end, a        distal mesh end, and a mesh length from the proximal end to the        distal end, the mesh being compressible to a collapsed        configuration for delivery to an endovascular treatment site        through a catheter and being self-expandable from the collapsed        configuration to an expanded configuration, and wherein, in a        longitudinal row of at least three cells, each cell distally        adjacent to another cell has a larger proximal inscribed strut        angle between first and second struts (i) bounding a proximal        portion of the cell and (ii) diverging in a distal direction,        than has the another cell.

23. The medical device of Clause 22, wherein the first and second strutscomprises a straight portion and a curved portion, and the inscribedstrut angle is measured between the straight portions of the first andsecond struts.

24. The medical device of Clause 22, wherein the inscribe strut angle ismeasured between straight reference lines that join strut intersectionpoints at each end of the first and second struts.

25. The medical device of Clause 22, wherein, for each cell, the firststrut has a length equal to that of the second strut.

26. The medical device of Clause 22, wherein the first struts of allcells between the first and second locations have the substantiallyequal lengths.

27. The medical device of Clause 22, wherein the longitudinal rowextends from a first location to a second location along the mesh, thefirst and second locations being longitudinally separated by a distancethat is more than half of the mesh length.

28. The medical device of Clause 27, wherein the first and secondlocations are longitudinally separated by a distance that is at leasttwo thirds of the mesh length.

29. The medical device of Clause 27, wherein the first and secondlocations are longitudinally separated by a distance that is at leastthree quarters of the mesh length.

30. The medical device of Clause 27, wherein the first and secondlocations are longitudinally separated by a distance that is at least90% of the mesh length.

31. The medical device of Clause 22, wherein the mesh is cylindrical inthe absence of external forces.

32. A medical device configured to perform an endovascular therapy, thedevice comprising:

-   -   an elongate manipulation member comprising a distal end portion;        and    -   an intervention member comprising a proximal end portion and a        plurality of cells forming a mesh, the proximal end portion        being coupled with the distal end portion of the elongate        manipulation member, the mesh having a proximal mesh end, a        distal mesh end, and a mesh length from the proximal end to the        distal end, the mesh being compressible to a collapsed        configuration for delivery to an endovascular treatment site        through a catheter and being self-expandable from the collapsed        configuration to an expanded configuration, and wherein, from a        first location to a second location along the mesh, each cell        distally adjacent to another cell, in a longitudinal row of        cells, has a larger maximum cell width than has the another        cell, the first and second locations being longitudinally        separated by a distance that is more than half of the mesh        length.

33. The medical device of Clause 32, wherein each cell comprises firstand second struts (i) bounding a proximal portion of the cell and (ii)diverging in a distal direction, and third and fourth struts (i)bounding a distal portion of the cell and (ii) converging in a distaldirection, the maximum cell width is measured from an intersection ofthe first strut and the third strut to an intersection of the secondstrut with the fourth strut.

34. The medical device of Clause 32, wherein, for each cell, the firststrut has a length equal to that of the second strut.

35. The medical device of Clause 32, wherein the first struts of allcell between the first and second locations have the substantially equallengths.

36. The medical device of Clause 32, wherein the first and secondlocations are longitudinally separated by a distance that is at leasttwo thirds of the mesh length.

37. The medical device of Clause 32, wherein the first and secondlocations are longitudinally separated by a distance that is at leastthree quarters of the mesh length.

38. The medical device of Clause 32, wherein the first and secondlocations are longitudinally separated by a distance that is at least90% of the mesh length.

39. The medical device of Clause 32, wherein the mesh is cylindrical inthe absence of external forces.

40. A medical device configured to perform an endovascular therapy, thedevice comprising:

-   -   an elongate manipulation member comprising a distal end portion;        and    -   an intervention member comprising a proximal end portion and a        plurality of sinuous members, the sinuous members connected to        form a mesh, the proximal end portion being coupled with the        distal end portion of the elongate manipulation member, the mesh        having a proximal mesh end, a distal mesh end, and a mesh length        from the proximal end to the distal end, the mesh being        compressible to a collapsed configuration for delivery to an        endovascular treatment site through a catheter and being        self-expandable from the collapsed configuration to an expanded        configuration, each sinuous member comprising a plurality of        oscillations, and wherein, from a first location to a second        location along the mesh, an amplitude of the oscillations of        each sinuous member increases in a distal direction, the first        and second locations being longitudinally separated by a        distance that is more than half of the mesh length.

41. The medical device of Clause 40, wherein the amplitude of theoscillations increases distally at a constant rate per unit length.

42. The medical device of Clause 40, wherein the frequency of theoscillations increases distally.

43. The medical device of Clause 40, wherein the first and secondlocations are longitudinally separated by a distance that is at leasttwo thirds of the mesh length.

44. The medical device of Clause 40, wherein the first and secondlocations are longitudinally separated by a distance that is at leastthree quarters of the mesh length.

45. The medical device of Clause 40, wherein the first and secondlocations are longitudinally separated by a distance that is at least90% of the mesh length.

46. The medical device of Clause 40, wherein the mesh is cylindrical inthe absence of external forces.

47. A medical device configured to perform an endovascular therapy, thedevice comprising:

-   -   an elongate manipulation member comprising a distal end portion;        and    -   an intervention member comprising a proximal end portion and a        plurality of struts forming a mesh, the proximal end portion        being coupled with the distal end portion of the elongate        manipulation member, the mesh comprising a plurality of        generally longitudinally arranged rows of cells and having a        proximal mesh end, a distal mesh end, and a mesh length from the        proximal end to the distal end, the mesh being compressible to a        collapsed configuration for delivery to an endovascular        treatment site through a catheter and being self-expandable from        the collapsed configuration to an expanded configuration, a        reference line for each row of at least three cells, each        reference line passing through all intersections of adjacent        cells in the corresponding row, and adjacent references lines        diverging distally.

48. The medical device of Clause 47, wherein, between the first andsecond locations, all of the reference lines continuously diverge fromeach adjacent reference line.

49. The medical device of Clause 47, wherein at least one referencesline is straight.

50. The medical device of Clause 47, wherein all of the references lineare straight.

51. The medical device of Clause 47, wherein each row extends from afirst location to a second location along the mesh, the first and secondlocations being longitudinally separated by a distance that is more thanhalf of the mesh length.

52. The medical device of Clause 51, wherein the first and secondlocations are longitudinally separated by a distance that is at leasttwo thirds of the mesh length.

53. The medical device of Clause 51, wherein the first and secondlocations are longitudinally separated by a distance that is at leastthree quarters of the mesh length.

54. The medical device of Clause 51, wherein the first and secondlocations are longitudinally separated by a distance that is at least90% of the mesh length.

55. The medical device of Clause 47, wherein the mesh is cylindrical inthe absence of external forces.

56. A medical device configured to perform an endovascular therapy, thedevice comprising:

-   -   an elongate manipulation member comprising a distal end portion;        and    -   an intervention member comprising a proximal end portion and a        plurality of struts forming a mesh, the proximal end portion        being coupled with the distal end portion of the elongate        manipulation member, the mesh having a proximal mesh end, a        distal mesh end, and a mesh length from the proximal end to the        distal end, the mesh being compressible to a collapsed        configuration for delivery to an endovascular treatment site        through a catheter and being self-expandable from the collapsed        configuration to an expanded configuration, and wherein, from a        first location to a second location along the mesh, each cell        distally adjacent to another cell has a strut that is more        deflectable than a strut of the another cell, the first and        second locations being longitudinally separated by a distance        that is more than half of the mesh length.

57. The medical device of Clause 56, wherein, from the first location tothe second location along the mesh, each cell distally adjacent toanother cell has a strut with a smaller cross-sectional dimension thanhas a strut of the another cell.

58. The medical device of Clause 57, wherein each strut distallyadjacent to another strut has a smaller cross-sectional dimension thanhas the another strut.

59. The medical device of Clause 57, wherein the cross-sectionaldimension is a strut width.

60. The medical device of Clause 57, wherein the cross-sectionaldimension is a strut thickness.

61. The medical device of Clause 57, wherein circumferentially adjacentstruts have substantially the same cross-sectional dimension.

62. The medical device of Clause 56, wherein the first and secondlocations are longitudinally separated by a distance that is at leasttwo thirds of the mesh length.

63. The medical device of Clause 56, wherein the first and secondlocations are longitudinally separated by a distance that is at leastthree quarters of the mesh length.

64. The medical device of Clause 56, wherein the first and secondlocations are longitudinally separated by a distance that is at least90% of the mesh length.

65. A method for restoring localized blood flow in a cerebral bloodvessel obstructed by a thrombus, comprising:

-   -   delivering an intervention member through a microcatheter to a        site of the thrombus in the cerebral blood vessel, the        intervention member comprising a mesh configured to self-expand        to assume an expanded configuration at the site, and to be        changed to a compressed configuration for delivery through the        microcatheter, the mesh configured to expand into the thrombus        when transitioning from the compressed configuration to the        expanded configuration;    -   expanding the mesh at the site, by proximally withdrawing the        microcatheter from over the structure, such that at least a        portion of the mesh expands into the thrombus; and    -   applying a proximally directed force to a proximal end of the        mesh to collapse, prior to withdrawal of the intervention member        into a catheter, a cell of a distal end of the mesh to at least        the same extent as a cell of a portion of the mesh proximal of        the distal end;    -   removing at least a portion of the thrombus by retracting the        intervention member.

66. The method of Clause 65, further comprising retracting the portionof the thrombus into a balloon catheter with the intervention member.

67. The method of Clause 65, wherein the intervention member iscylindrical in the absence of external forces.

68. The method of Clause 65, wherein the proximally directed force isapplied to a proximal end of the mesh to collapse, prior to withdrawalof the intervention member into a catheter, a distal end of the mesh toa greater extent than the portion of the mesh proximal of the distalend.

69. The method of Clause 65, wherein collapsing the cell of the distalend of the mesh comprises reducing a maximum width of the cell of thedistal end to at least the same extent as a maximum width of the cell ofthe portion of the mesh proximal of the distal end.

70. The method of Clause 65, further comprising gripping the thrombuswith the cell of the distal end to at least the same extent as with thecell of the portion of the mesh proximal of the distal end.

71. The method of any of Clauses 65-70, performed with the device of anyof Claims 1-64 or 69-75.

69. A medical device configured to perform an endovascular therapy, thedevice comprising:

-   -   an elongate manipulation member comprising a distal end portion;        and    -   an intervention member comprising a proximal end portion and a        mesh, the proximal end portion being coupled with the distal end        portion of the elongate manipulation member, the mesh having a        proximal mesh end, a distal mesh end, and a mesh length from the        proximal end to the distal end, the mesh having a plurality of        cells and being compressible to a collapsed configuration for        delivery to an endovascular treatment site through a catheter        and being self-expandable from the collapsed configuration to an        expanded configuration, and wherein at least a portion of the        mesh, from a first location to a second location along the mesh,        is configured such that an amount of thrombus engagement in        response to longitudinally directed tensile forces decreases by        less than 5% or increases in a distal direction along the        portion of the mesh, the first and second locations being        longitudinally separated by a distance that is more than half of        the mesh length.

70. The medical device of Clause 69, wherein the portion of the mesh,from the first location to the second location along the mesh, isconfigured such that the amount of thrombus engagement in response tolongitudinally directed tensile forces does not decrease in a distaldirection along the portion of the mesh.

71. The medical device of Clause 69, wherein the portion of the mesh,from the first location to the second location along the mesh, isconfigured such that the amount of thrombus engagement in response tolongitudinally directed tensile forces increases in a distal directionalong the portion of the mesh.

72. The medical device of Clause 69, wherein the first and secondlocations are longitudinally separated by a distance that is at leasttwo thirds of the mesh length.

73. The medical device of Clause 69, wherein the first and secondlocations are longitudinally separated by a distance that is at leastthree quarters of the mesh length.

74. The medical device of Clause 69, wherein the first and secondlocations are longitudinally separated by a distance that is at least90% of the mesh length.

75. The medical device of Clause 69, wherein the mesh is cylindrical inthe absence of external forces.

Additional features and advantages of the subject technology will be setforth in the description below, and in part will be apparent from thedescription, or may be learned by practice of the subject technology.The advantages of the subject technology will be realized and attainedby the structure particularly pointed out in the written description andclaims hereof as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the subject technology asclaimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide furtherunderstanding of the subject technology and are incorporated in andconstitute a part of this description, illustrate aspects of the subjecttechnology and, together with the specification, serve to explainprinciples of the subject technology.

FIG. 1 illustrates a device, including an expandable member, for bloodflow restoration, thrombus removal, or both, according to an embodiment.

FIG. 2 illustrates an expandable member, according to an embodiment, inan unrolled state.

FIG. 3 is a schematic illustration of overlap configurations of theexpandable member of FIG. 2, as viewed from a distal end of theexpandable member.

FIGS. 4A-D are schematic illustrations of overlap configurations of theexpandable member of FIG. 2, as viewed from a side of the expandablemember.

FIG. 5 illustrates an expandable member in an unrolled state.

FIGS. 6A and 6B illustrate change in lateral cell width for variouslocations along expandable members.

FIGS. 7A and 7B illustrate associated contact reaction stress of theclot for various locations along expandable members, as a consequence ofthe change in lateral cell width illustrated in FIGS. 6A-6B.

FIG. 8 illustrates an expandable member, according to an embodiment, inan unrolled state.

FIG. 9 illustrates an expandable member, according to an embodiment, inan unrolled state.

FIG. 10 illustrates an expandable member, according to an embodiment, inan unrolled state.

FIGS. 11A-11D schematically illustrate thrombi located in various vesselarrangements.

FIG. 12 schematically illustrates a system for blood flow restoration,thrombus removal, or both.

FIGS. 13-22 are cross-sectional views of a vessel and illustrate use ofa device according to some embodiments.

DETAILED DESCRIPTION

The detailed description set forth below is intended as a description ofvarious configurations of the subject technology and is not intended torepresent the only configurations in which the subject technology may bepracticed. The appended drawings are incorporated herein and constitutea part of the detailed description. The detailed description includesspecific details for the purpose of providing a thorough understandingof the subject technology. However, the subject technology may bepracticed without these specific details. In some instances, well-knownstructures and components are shown in block diagram form in order toavoid obscuring the concepts of the subject technology.

FIG. 1 depicts a medical device 100 according to some embodiments of thesubject technology. As illustrated in FIG. 1, the medical device 100 cancomprise an expandable member 102 and a manipulation member 104. Aproximal end portion of the expandable member 102 and a distal endportion of the manipulation member 104 can be joined at a connection106. The manipulation member 104 can extend through a catheter 107 suchthat an operator can manipulate the expandable member 102, positionedwithin and/or distal to a distal end of the catheter 107, using themanipulation member 104 at a location proximal to a proximal end of thecatheter 107.

The manipulation member 104 can have a length sufficient to extend froma location outside the patient's body through the vasculature to atreatment site within the patient's body. The manipulation member 104can be monolithic or formed of multiple joined components. In someembodiments, the manipulation member 104 can comprise a combination ofwire(s), coil(s), and/or tube(s). The manipulation member 104 cancomprise one or more markers, e.g., comprised of radiopaque material(s)to aid radiographic visualization during manipulation.

The expandable member 102 and the manipulation member 104 can besubstantially permanently attached together at the connection 106. Thatis, the expandable member 102 and the manipulation member 104 can beattached together in a manner that, under the expected use conditions ofthe assembly 100, the endovascular device and the manipulation memberwould not become unintentionally separated from one another.

Depending on the procedure and intended use of the medical device 100,it optionally may be advantageous to have a connection mechanism thatpermits intentional release of the medical device 100. For example,during a blood flow restoration procedure, it may prove difficult and/ordangerous to fully retrieve a thrombus due to a complicated vasculatureor the risk of damaging a lumen wall. Leaving the medical device 100inside the patient may prove to be the only option available to asurgeon or other medical personnel, or it may be a goal of theprocedure, such as when the device 100 is deployed across an aneurysm(e.g., as an aneurysm bridge to retain coils or other materials in ananeurysm). In other circumstances the medical device 100 may includedrug-eluting capabilities, and/or may be coated with a particular typeof drug that facilitates thrombus dissolution. It may be advantageous insuch circumstances to release the medical device 100 and allow themedical device 100 to anchor the thrombus against the lumen wall whilethe thrombus is dissolved by the drug. In some embodiments, the medicaldevice 100 can comprise a portion, located proximally or distally of theconnection 106, that is configured for selective detachment of theendovascular device 102 from the manipulation member 104. For example,such a portion can comprise an electrolytically severable segment of themanipulation member. In some embodiments, the assembly 100 can be devoidof any feature that would permit selective detachment of theendovascular device 102 from the manipulation member 104.

Further details regarding connections that can be employed between theexpandable member 102 and the manipulation member 104 disclosed in U.S.Pat. No. 7,300,458, entitled Medical Implant Having a Curable MatrixStructure, issued Nov. 27, 2007; U.S. Patent Application Publication No.2011/0060212, entitled Methods and Apparatus for Flow Restoration,published on Mar. 10, 2011; U.S. Patent Application Publication No.2012/0083868, entitled Methods and Apparatuses for Flow Restoration andImplanting Members in the Human Body, published on Apr. 5, 2012; U.S.Patent Application Publication No. 2011/0160763, entitled Blood FlowRestoration in Thrombus Management Methods, published on Jun. 30, 2011;U.S. patent application Ser. No. 13/834,945, entitled Connection of anEndovascular Intervention Device to a Manipulation Member, filed on Mar.15, 2013, published as ______ on ______; and U.S. patent applicationSer. No. 13/835,130, entitled Connection of a Manipulation Member,Including a Bend without Substantial Surface Cracks, to an EndovascularIntervention Device, filed on Mar. 15, 2013, published as ______ on______; the entirety of each of which is hereby incorporated byreference herein.

FIG. 2 is a plan view showing the expandable member 102 in an unrolledstate to facilitate description and understanding. As illustrated inFIGS. 1 and 3, the expandable member 102 can have a tubular or generallycylindrical shape in absence of external forces in some embodiments. Theexpandable member 102 can be self-expanding, e.g. by super-elasticity orshape memory, or expandable in response to forces applied on theexpandable member, e.g. by a balloon.

As illustrated in FIGS. 1 and 2, the expandable member 102 can comprisea frame 108 having a proximal end 110 and a distal end 112. The framecan comprise a plurality of struts 114 and a plurality of cells 116forming a mesh. Groups of longitudinally and serially interconnectedstruts 114 can form undulating members 118 that extend in a generallylongitudinal direction. The struts 114 can be connected to each other byjoints 120. While the struts are shown having a particular undulating orsinuous configurations, in some embodiments the struts can have otherconfigurations. The frame can have a generally tubular or generallycylindrical shape with one or both of the proximal end 110 and thedistal end 112 being open.

As illustrated in FIGS. 1 and 2, a proximal portion 122 of theexpandable member 102 can be tapered toward the proximal end 110. Insome embodiments, the taper of the proximal portion can advantageouslyfacilitate retraction and repositioning of the device 10 and expandablemember 102. In some embodiments, the tapered proximal portion can alsobe designed to generally not contact the vessel wall during a blood flowrestoration procedure, and to generally not interfere with the flow ofblood within a vessel.

Individual cells of the proximal portion 122 can have different sizesthan individual cells located distal to the tapered proximal portion.For example, in some embodiments, the proximal portion 122 can haveindividual cells that have a size larger than that of the individualcells located distal to the tapered proximal portion. The proximalportion 122 can taper gradually towards the connection 106.

The taper of proximal portion 122 can be at various angles relative tothe manipulation member 104. For example, in some embodiments, the tapercan have an angle of approximately 45 degrees relative to themanipulation member, though other angles are also possible.

The expandable member 102 can comprise a first edge 124 and a secondedge 126. The first edge 124 and second edge 126 can be formed, forexample, from cutting a sheet or a tube. While the first and secondedges are shown as having an undulating, or sinuous configuration, insome embodiments the first and second edges can have a straight, orlinear configuration, or other configuration. In some embodiments, theedges 124, 126 can be curved, straight, or a combination thereof alongthe tapered proximal portion 122.

Referring to FIGS. 3 and 4A-D, the expandable member 102 can be curled,rolled, or otherwise formed such that first edge 124 and second edge 126overlap one another when the expandable member 102 is in avolume-reduced form. In a volume-reduced form, the frame 102 of theexpandable member 102 can overlap to facilitate introduction of theexpandable member 102 into and through the catheter 107. In someembodiments, the expandable member 102 is circumferentially continuous(e.g., forming a continuous cylindrical shape), lacking first and secondedges 124, 126 and having no overlap or gap in a volume-reduced form andexpanded form. Regardless of whether the expandable member iscircumferentially continuous, the expandable member 102 can have acentral longitudinal axis both while in a volume-reduce form and whenfully or partially expanded. In some embodiments, the expandable member102 can be self-expandable, and can expand toward a fully expandedconfiguration upon release from the catheter 107. Upon expansion, theexpandable member 102 can expand towards an inner wall of a vessel,towards a thrombus occluding the inner wall of a vessel, or both.

FIGS. 4A-4D illustrate various amounts of overlap of the frame 108 ofthe expandable member 102. The extent of any overlap of the frame 108can depend upon a degree of the frame's expansion. Expansion within avessel can be limited, at least in part, by the vessel's size, and theamount and the properties of any thrombus present. For example, agreater overlap of the edges 124, 126 can occur in narrower vessels,whereas in wider vessels the overlap can be smaller, or even an“underlap” may occur, in which case the edges 22 and 24 are separated byan open gap or space within the vessel.

With continued reference to FIGS. 3 and 4A-D, embodiments of theexpandable member 102 can experience various degrees of overlap in avolume-reduced form, forming zones of overlap 128. The expandable member102 can assume various diameters Δ₁, Δ₂, etc., depending on the degreeof the overlap (e.g. represented by angle α₁, α₂, etc.). As illustratedin FIGS. 4A-D, the overlap zones 128 can vary in size and configurationdepending on the vessel size. When inside a vessel, the overlap zone ofthe expandable member 102 can advantageously provide grip and/orretaining ability with respect to a thrombus. For example, when theexpandable member 102 expands against a thrombus, the individual struts114 and individual cells 116 of the overlap zone can embed into andgrip, or retain, the thrombus. Alternatively, the expandable member 102can be constructed without any overlap or edges 124, 126, e.g. as acontinuous tubelike or cylindrical member.

The expandable member 102 can be manufactured in various lengths andrelaxed-state diameters. In some embodiments, the expandable member 102can have lengths, measured proximally to distally along the longitudinalaxis, of 15 mm or less to 40 mm or more, though other ranges and sizesare also possible. The expandable member 102 can also have relaxed-statediameters, the diameters being measured when the expandable member 102is fully free to expand, i.e., in absence of external forces. In someembodiments, the expandable member 102 can have a diameter ofapproximately 3 mm to 4 mm so as to be used in size 18 microcatheters(i.e. microcatheters with an inner diameter of approximately 0.21 inch).In some embodiments the expandable member 102 can have a diameter ofapproximately 5 mm to 6 mm so as to be used in size 27 microcatheters(i.e. microcatheters with an inner diameter of approximately 0.027inch). Other ranges and values are also possible.

Each cell 116 of the expandable member 102 can have a maximum length(labeled “L” in FIG. 2), as measured along a longitudinal axis of theexpandable member 102, and a maximum width W, as measured along adirection generally perpendicular to the length (labeled “W” in FIG. 2).In some embodiments, cell size and dimensions can vary, as can theindividual filament thicknesses and widths.

The location and longitudinal extent of thrombus engagement by amechanical thrombus-retrieval device, e.g., the expandable member 102,can affect the likelihood of successfully capturing the engagedthrombus. Some embodiments of the subject technology increase thelikelihood of successful thrombus capture and retrieval by increasing alongitudinal extent of substantially even thrombus engagement, distallyshifting the region of increased thrombus engagement, or both. When athrombus is primarily engaged along a portion of the thrombus near itsproximal end, and particularly when a longitudinal extent ofsubstantially even thrombus engagement is small, the thrombus may bemore likely to fragment, become released from the retrieval device, orboth.

In some embodiments, the expandable member 102 can be configured forsubstantially uniform or distally biased thrombus engagement, afterexpansion of the expandable member 10 into the thrombus, duringretrieval of thrombus from a vessel by proximal retraction of themanipulation member 104. The thrombus can be generally soft, ormalleable, or generally hard, or callous. For example, the expandablemember 102 can have strut and cell dimensions that provide substantiallyuniform or distally biased thrombus engagement.

FIG. 5 illustrates an expandable member 102 having a pattern 130 ofcells 116 of substantially uniform dimensions and of struts 114 ofsubstantially uniform dimensions. The pattern of cells and struts ofFIG. 5 is substantially uniformly flexible or deformable. However, whenthe expandable member of FIG. 5 is embedded in a thrombus and aproximally directed force is applied at a proximal end 110 of theexpandable member, the cells of the expandable member tend to collapsein width, and therefore engage a thrombus, more along a proximal portionof the substantially uniform pattern 130 than they do along a distalportion of the substantially uniform pattern 130. Such a proximallydirected force may be considered to simulate the force exerted on theproximal end 110, via the manipulation member 104, during retrieval ofthe expandable member 102 in a procedure to remove, e.g., thrombus froma blood vessel.

FIGS. 6A and 6B illustrate the amount of change (reduction) in (e.g.,maximum) cell width W observed for cells in various longitudinalpositions along the length of the frame 108, upon application of aproximally directed force at a proximal end of the frame when embeddedin simulated thrombus having an outer extent fixed in six degrees offreedom. FIG. 6A is an exemplifying plot of the amount of change(reduction) in (maximum) cell width (resulting from such forceapplication) against longitudinal position for a frame having asubstantially uniform cell angle or pattern 130. As indicated by FIG.6A, the amount of change in maximum cell width diminishes with distancefrom the proximal end for a frame having a substantially uniform pattern130. Thus, an expandable member having a substantially uniform pattern130 “pinches” the thrombus more (by virtue of a greater reduction incell width) along a proximal portion of the thrombus than it does alonga distal portion of the thrombus.

FIG. 6B is an exemplifying plot of the amount of change (reduction) in(maximum) cell width against the longitudinal position for frames insome embodiments of the subject technology, for example such as thoseillustrated in FIGS. 2, 8, 9, and 10. In contrast to FIG. 6A, FIG. 6Bindicates that the amount of reduction in maximum cell width increaseswith distance from the proximal end for frames according to someembodiments of the subject technology. Thus, an expandable memberaccording to some embodiments of the subject technology pinches andgrips the thrombus more along a distal portion of the thrombus than itdoes along a proximal portion of the thrombus. Therefore, expandablemembers according to some embodiments of the subject technology can beless likely to fragment the thrombus, release the thrombus, or bothduring retrieval, compared to an expandable member having asubstantially uniform pattern 130.

FIGS. 7A and 7B indicate the resultant contact reaction stresses (due tothe cell width reduction) between the frame and thrombus in cells atvarious longitudinal positions along the length of the frame, uponapplication of a proximally directed force at a proximal end of theframe when embedded in simulated thrombus having an outer extent fixedin six degrees of freedom. FIG. 7A is an exemplifying plot of contactreaction stress against longitudinal position for a frame, asillustrated in FIG. 5 for example, wherein longitudinally and laterallyadjacent cells have substantially the same dimensions and the strutssurrounding those cells have substantially the same dimensions. Asindicated by FIG. 7A, contact reaction stress diminishes with distancefrom the proximal end for a frame having a substantially uniform pattern130. Thus, an expandable member having a substantially uniform pattern130 tends to pull on the thrombus, during retraction, more along aproximal portion of the thrombus than it does along a distal portion ofthe thrombus.

FIG. 7B is an exemplifying plot of contact reaction stress againstlongitudinal position for frames in some embodiments of the subjecttechnology, for example such as those illustrated in FIGS. 2, 8, 9, and10. In contrast to FIGS. 7A, FIG. 7B indicates that contact reactionstress increases, along at least a portion of the frame's length, withdistance from the proximal end for frames according to some embodimentsof the subject technology. Thus, an expandable member according to someembodiments of the subject technology tends to pull on the thrombus lessalong a proximal portion of the thrombus than it does along a portion ofthe thrombus distal to the proximal portion. Therefore, expandablemembers according to some embodiments of the subject technology can beless likely to fragment the thrombus, release the thrombus, or bothduring retraction, compared to an expandable member having asubstantially uniform pattern 130.

FIGS. 8-10 illustrate expandable members 102, according to embodimentsof the subject technology, in plan view, e.g., an unrolled state. Theexpandable members 102 of FIGS. 8-10 are examples of the expandablemember 102 described above with reference to FIGS. 2-4D. Accordingly,the description of the expandable member 102 with reference to FIGS.2-4D also applies to expandable members 102 of FIGS. 8-10.

The expandable members 102 of FIGS. 8-10 can provide distally biasedthrombus engagement, as described above with reference to FIGS. 6Band/or 7B, substantially uniform thrombus engagement, or a combinationthereof over lengthwise portions of the expandable member. Thrombusengagement can be considered substantially uniform when the amount ofchange in maximum cell width and/or contact reaction stress varies inthe longitudinal direction by less than 5% upon application of aproximally directed force at a proximal end of the expandable memberwhen the expandable member is embedded in thrombus, or simulatedthrombus, having an outer extent fixed in six degrees of freedom.

In some embodiments, at least a portion of the frame 108, from a firstlocation to a second location along the frame, is configured such thatan amount of cell deformation or deflection in response tolongitudinally directed tensile forces decreases by less than 5% orincreases in a distal direction along a portion of the frame. The celldeformation can be, for example, change of maximum cell width. In someembodiments, the amount of cell deformation in response tolongitudinally directed tensile forces does not decrease in a distaldirection along the portion of the frame. In some embodiments, theamount of cell deformation in response to longitudinally directedtensile forces continuously increases in a distal direction along theportion of the frame. The portion of the frame can extend from a firstlocation to a second location along the frame. In some embodiments, thefirst and second locations can be longitudinally separated by a distancethat is more than half of the mesh length, at least two thirds of theframe length, at least three quarters of the frame length, or at least90% of the frame length. In some embodiments, portion of the frame cancomprise a longitudinal row of at least two, three, or four cells.

In some embodiments, at least a portion of the frame 108, from a firstlocation to a second location along the frame, is configured such thatan amount of thrombus engagement in response to longitudinally directedtensile forces decreases by less than 5% or increases in a distaldirection along a portion of the frame. The thrombus engagement can be,for example, contact reaction stress. In some embodiments, the amount ofthrombus engagement in response to longitudinally directed tensileforces does not decrease in a distal direction along the portion of theframe. In some embodiments, the amount of thrombus engagement inresponse to longitudinally directed tensile forces continuouslyincreases in a distal direction along the portion of the frame. Theportion of the frame can extend from a first location to a secondlocation along the frame. In some embodiments, the first and secondlocations can be longitudinally separated by a distance that is morethan half of the mesh length, at least two thirds of the frame length,at least three quarters of the frame length, or at least 90% of theframe length. In some embodiments, portion of the frame can comprise alongitudinal row of at least two, three, or four cells.

FIG. 8 illustrates an expandable member 102 wherein, in a portion of theframe 108 in a relaxed state, each cell distally adjacent to anothercell, in a longitudinal row of cells, has a larger proximal inscribedstrut angle θ between first and second struts (i) bounding a proximalportion of the cell and (ii) diverging in a distal direction, than hasthe another cell. For example, FIG. 8 shows a first cell 132 having aproximal inscribed strut angle θ₁, a second cell 134 having a proximalinscribed strut angle θ₂, a third cell 136 having a proximal inscribedstrut angle θ₃, and a fourth cell having a proximal inscribed strutangle θ₄, wherein θ₄>θ₃>θ₂>θ₁. The portion of the frame can extend froma first location to a second location along the frame. In someembodiments, the first and second locations can be longitudinallyseparated by a distance that is more than half of the mesh length, atleast two thirds of the frame length, at least three quarters of theframe length, or at least 90% of the frame length. In some embodiments,portion of the frame can comprise a longitudinal row of at least two,three, or four cells.

In some embodiments, the proximal inscribed strut angle θ can bemeasured between substantially straight portions 140 of the struts 114,as illustrated in FIG. 8. In some embodiments, the proximal inscribedstrut angle θ can be measured between straight reference lines thatconnect a joint 120 a, at a proximal end of a cell, with opposinglaterally positioned joints 120 b, 120 c, respectively, at of that cell.In either case, each strut 114 can be straight, curved, or comprisestraight portion(s) and curved portion(s).

In addition or alternative to distally increasing, proximal inscribedstrut angles, the expandable member 102 can have a portion of the frame108 wherein, in a relaxed state, each cell distally adjacent to anothercell, in a longitudinal row of cells, has a larger interior bounded areathan has the another cell. For example, an interior bounded area offourth cell 138 can be larger than an interior bounded area of thirdcell 136, which can be larger than an interior bounded area of secondcell 134, which can be larger than an interior bounded area of firstcell 132. The portion of the frame can extend from a first location to asecond location along the frame. In some embodiments, the first andsecond locations can be longitudinally separated by a distance that ismore than half of the mesh length, at least two thirds of the framelength, at least three quarters of the frame length, or at least 90% ofthe frame length. In some embodiments, portion of the frame can comprisea longitudinal row of at least two, three, or four cells.

In some embodiments, the expandable member 102 can have a portion of theframe 108 wherein, in a relaxed state, each cell distally adjacent toanother cell, in a longitudinal row of cells, has a larger maximum cellwidth W than has the another cell. For example, a maximum cell width offourth cell 138 can be larger than a maximum cell width of third cell136, which can be larger than a maximum cell width of second cell 134,which can be larger than a maximum cell width of first cell 132. Theportion of the frame can extend from a first location to a secondlocation along the frame. In some embodiments, the first and secondlocations can be longitudinally separated by a distance that is morethan half of the mesh length, at least two thirds of the frame length,at least three quarters of the frame length, or at least 90% of theframe length. In some embodiments, portion of the frame can comprise alongitudinal row of at least two, three, or four cells.

Accordingly, the herein-discussed configurations of the expandablemember 102 (distally increasing maximum cell width W, distallyincreasing cell area, distally increasing proximal included strut angleθ, distally increasing amplitude A, distally diverging reference lines144, and/or distally increasing strut flexibility/deflectability) caneach be considered a means for engaging a thrombus (or other material)in a substantially uniform (and/or distally biased) manner along thelength of the expandable member 102.

In the embodiment of FIG. 8, maximum cell length can range from 3.50 mmto 5.50 mm in a relaxed state, though other ranges and values are alsopossible, and maximum cell width can range from between 2.50 mm to 4.50mm and a relaxed state, though other ranges and values are alsopossible. All of the foregoing dimensions can optionally be implementedalone or in any combination without departing from the scope of thisdisclosure.

FIG. 9 illustrates an expandable member 102 comprising a plurality ofundulating or sinuous members 118. Each undulating or sinuous member 118can comprise a plurality of oscillations 142. Each oscillation can havean amplitude (labeled “A” in FIG. 9). In some embodiments, anoscillation can correspond in length to the length of a cell. Anoscillation 142 can comprise one or more struts 114. Some embodimentscan comprise a portion of the frame 108 wherein, in a relaxed state,each oscillation of each undulating or sinuous member 118 does notdecrease, or alternatively, increases in a distal direction compared toa proximally adjacent oscillation. In some embodiments, the amplitude ofthe oscillations can increase distally at a constant rate per unitlength. The portion of the frame can extend from a first location to asecond location along the frame. In some embodiments, the first andsecond locations can be longitudinally separated by a distance that ismore than half of the mesh length, at least two thirds of the framelength, at least three quarters of the frame length, or at least 90% ofthe frame length. In some embodiments, portion of the frame can comprisea longitudinal row of at least two, three, or four cells.

FIG. 9 illustrates a plurality of reference lines 144. Each referenceline can pass through all joints 120 between adjacent cells in a row ofcells. Some embodiments can comprise a portion of the frame 108 wherein,in a relaxed state, each reference line 144 continuously diverges fromat least one or two adjacent reference lines 144. In some embodiments,the reference lines can be straight. In some embodiments, all or aportion of respective reference line can be curved. The portion of theframe can extend from a first location to a second location along theframe. In some embodiments, the first and second locations can belongitudinally separated by a distance that is more than half of themesh length, at least two thirds of the frame length, at least threequarters of the frame length, or at least 90% of the frame length. Insome embodiments, the portion of the frame can comprise a longitudinalrow of at least two, three, or four cells.

In some embodiments, the expandable member 102 can have a portion of theframe 108 wherein, in a relaxed state, each cell distally adjacent toanother cell can have a strut that is more flexible or deflectable thana strut of the another cell. In some embodiments, each strut distallyadjacent to another strut can be more flexible or deflectable than isthe another strut. Strut flexibility or delectability can be increased,for example, by diminishing strut thickness, strut width, or both alongall or a portion of the strut's length. The portion of the frame canextend from a first location to a second location along the frame. Insome embodiments, the first and second locations can be longitudinallyseparated by a distance that is more than half of the mesh length, atleast two thirds of the frame length, at least three quarters of theframe length, or at least 90% of the frame length. In some embodiments,portion of the frame can comprise a longitudinal row of at least two,three, or four cells.

The struts 114 can have individual strut widths “a” (FIG. 10) that rangefrom 0.010 in. to 0.025 in., and individual strut thicknesses “b” thatrange from 0.045 mm to 0.080 mm, though other ranges and values forindividual strut width and thickness are also possible. Widths “a” asdescribed herein can generally be measured as illustrated by the arrowsin FIG. 10. Thicknesses “b” as described herein can generally bemeasured as illustrated by the arrows in FIG. 3 (e.g. in a directionextending out of the page of FIG. 10, and perpendicular to themeasurement for width “a”). The widths “a” can be measured, for example,using a system such as the Visicon Automated Inspection System, or othersuitable system. The thicknesses “b” can be measured, for example, usinga system such as the Heidenhain Inspection System, or other suitablesystem.

With continued reference to FIG. 10, the joints 120 can have anindividual strut thickness “b” that range from 0.050 mm to 0.0825 mm andan individual strut width “a” that ranges from 0.050 mm to 0.0825 mm,though other ranges and values are also possible. In some embodiments,individual struts can have individual strut thicknesses “b” that rangefrom 0.040 mm to 0.075 mm, and individual strut widths “a” that rangefrom 0.038 mm to 0.082 mm, though other ranges and values are alsopossible. In some embodiments, the individual struts in a portion of theexpandable member 102 can have average strut thicknesses “b” that rangefrom 0.048 mm to 0.067 mm, and individual strut widths “a” that averagefrom 0.053 mm to 0.067 mm, though other ranges for average values arealso possible.

FIG. 10 illustrates an example of an embodiment wherein strut thicknessis diminished in a distal direction, thereby distally increasing strutflexibility or to flexibility. The frame 108 of the expandable member102 in FIG. 10 comprises a plurality of rings 146, 148, 150, 152, 154,156, 158 of circumferentially adjacent struts. The struts 114 in eachring can have substantially the same width, as illustrated, for example,in FIG. 10. In some embodiments, circumferentially adjacent struts canhave different widths. Referring again to FIG. 10, the strut width ofeach ring 146, 148, 150, 152, 154, 156, 158 can diminish in the distaldirection. In other words, a strut width of ring 158 can be less than astrut width of ring 156, which can be less than a strut width of ring of154, which can be less than a strut width of ring 152, which can be lessthan a strut width of ring 150, which can be less than a strut width ofring 148, which can be less than a strut width of ring 146. In someembodiments, two or more longitudinally adjacent struts, or rings ofstruts, can have the same, or substantially the same, width. Forexample, struts 114 distal to the ring 158 can have the same, orsubstantially the same, strut width as the struts of ring 158.

Although FIG. 10 illustrates the struts 114 as having substantiallyconstant widths along their entire respective lengths, the struts canhave widths that vary along their lengths in some embodiments. Forexample, the struts can have an hourglass shape, can be wider in themiddle than at the ends, can have corrugated edges, or have otherconfigurations. Strut thickness can likewise be constant or variablealong each strut's length. The struts' cross-sectional areas canlikewise be constant or variable along each strut's length.

In the embodiment of FIG. 10, maximum cell length can range from 3.50 mmto 5.50 mm in a relaxed state, though other ranges and values are alsopossible and within the scope of this disclosure, and maximum cell widthcan range from between 2.50 mm to 4.50 mm and a relaxed state, thoughother ranges and values are also possible and within the scope of thisdisclosure.

The expandable member 102 can generate specific forces once it isdeployed and released from the catheter 107 for engagement and removalof thrombi. By deploying the expandable member 102 in or across athrombus, the expandable member 102 can be expanded, e.g., self-expandedto a larger diameter due to elastic energy stored in the expandablemember 102. The expandable member 102 can expand in the vessel untilequilibrium is reached between the stored elastic energy and an opposingforce from the surrounding vessel wall and/or thrombus. The struts 114and cells 116 of the expandable member 102 can penetrate a thrombus,promoting adhesion and embedment of the thrombus to the expandablemember 102, and the expanding force of the expandable member 102 canpromote dislodgment of the thrombus from the vessel wall.

For example, the stored elastic energy of the expandable member 102 cangenerate outward forces known as radial force (RF) and chronic outwardforce (COF). The radial force is equivalent to the outward force exertedby the expandable member 102 during compression of the expandable member102. The chronic outward force is equivalent to the outward forceexerted by the expandable member 102 during decompression, or expansion,of the expandable member 102. In a preferred arrangement, the COF can bedesigned so that it is not so high that it bursts, or damages, a vesselwall. In a preferred arrangement, the RF can be designed so that it ishigh enough to resist compression forces from the surrounding vesselenvironment, maintain patency of the vessel lumen, and restore flowthrough the thrombus site.

During deployment and thrombus retrieval, the highest COF and RF canoccur when the expandable member 102 is deployed and/or retrieved insidea minimum recommended diameter vessel. Conversely, the COF and RF can bethe lowest when the expandable member 102 is deployed and/or retrievedinside a maximum recommended diameter vessel. In some embodiments, acurled, overlapped expandable member 102 can enhance the COF and RF,particularly in smaller diameter vessels, to allow for increasedembedment of a thrombus to the expandable member 102.

The radial force can be measured by various methods. For example, a twopin method can measure the radial force by placing (e.g. sliding) theexpandable member 102 over two elongate, parallel pins, such that thegenerally tubular, expandable member 102 encompasses and surrounds thetwo pins. When placed over the two pins, the proximal end 110 ofproximal portion 122 can be located generally halfway between the twoelongate pins, and to one side. The ends of the two pins can be placedin a tensile testing machine. When the testing machine is loaded, themachine can cause the pins to pull apart from one another, such that aforce is imparted on the expandable member 102. When the expandablemember 102 slips off of one of the pins, the radial force can bemeasured.

A thin film method can also be used to measure the radial force, and canadditionally be used to measure the chronic outward force. The thin filmmethod can generally comprise compressing and decompressing theexpandable member 102 circumferentially 360 degrees using a thin film ofPTFE wrapped around the expandable member 102. The thin film method canmeasure changes in diameter of the expandable member 102 versus forcefor both expansion and contraction of the expandable member 102.

In a preferred arrangement using the thin film method, the expandablemember 102 can have a radial force measurement greater than or equal to0.0010 N per mm of length of the portion of the expandable member 102that is configured to contact a vessel wall or thrombus (e.g. distalportion 30). The length in this unit refers to a proximal to distaldirection measurement (i.e. moving left to right in FIG. 1). Instead ofor in addition to the foregoing, the expandable member 102 can have achronic outward force of less than or equal to 0.026 N per mm (orbetween about 0.001 N/mm and 0.026 N/mm) of length of the portion of theexpandable member 102 that is configured to contact a vessel wall orthrombus, depending on the inner diameter of the vessel in which theexpandable member is deployed. In a preferred arrangement using the twopin method, the expandable member 102 can have a radial forcemeasurement of between approximately 6 to 37 (or between approximately 0to 50) gf per inch of length of the portion of the expandable member 102that is configured to contact a vessel wall or thrombus. Other valuesfor the foregoing variables are possible and within the scope of thisdisclosure.

In some embodiments, the expandable member 102 can further include atleast one distal marker 160. The distal marker 160 can be attached to orintegrally formed with a distal portion of the expandable member 102.The distal marks 160 can comprise, for example, a band comprisingplatinum, gold, and/or other radiopaque materials. The markers 160 canbe used during an imaging process to identify a location or locations ofthe expandable member 102 during a blood flow restoration procedure. PCTPublication No. WO 2009/105710, which is incorporated by reference inits entirety, describes various uses of marker bands and imaging of anexpandable member 102.

The frame 108 can be formed, for example, by cutting a sheet or tube(e.g., by laser, etching, etc.), by interconnecting a multitude offilaments by laser welding, or by other suitable methods. In someembodiments, the expandable member 102 can be initially laser cut from atube. In some embodiments, the expandable member 102 can be formed bycutting a pattern on a flat sheet and then rolling the flat sheet into agenerally tube-like or coiled shape. The joints 120 may be formed bywelding, soldering, or otherwise joining the struts 114. Other methodsfor forming the expandable member 102 are also possible.

In some embodiments, the expandable member 102 can comprise metal,polymer, ceramic, permanent enduring materials, and may comprise eitherof or both of non-bioabsorbable and bioabsorbable materials. Exemplarymaterials include, but are not limited to, NITINOL®, stainless steel,cobalt chromium alloys, Elgiloy, magnesium alloys, polylactic acid, polyglycolic acid, poly ester amide (PEA), poly ester urethane (PEU), aminoacid based bioanalogous polymers, tungsten, tantalum, platinum,polymers, bio-polymers, ceramics, bio-ceramics, or metallic glasses.Part or all of the expandable member may elute over time substances suchas drugs, biologics, gene therapies, antithrombotics, coagulants,anti-inflammatory drugs, immunomodulator drugs, anti-proliferatives,migration inhibitors, extracellular matrix modulators, healingpromoters, re-endothelialization promoters, or other materials. In someembodiments, the expandable member may be formed from materials havingshape memory properties. In some embodiments, the expandable member maybe finished by processes to remove slag. In some embodiments, theexpandable member may be subjected to a tempering treatment attemperatures customarily applied to the material so that the impressedstructure is permanently established.

Referring to FIGS. 11A-D, in some embodiments the expandable member 102can be used as a flow restoration device and/or an implantable member(e.g. stent) in a vessel, including at bifurcation, bi-vessel, and/ormulti-vessel locations. For example, and with reference to FIG. 11A,thrombi can be located at bifurcations in the neurovasculature such asthe internal carotid artery and the anterior cerebral artery, orinternal carotid artery and middle cerebral artery, or the basilarartery and the posterior cerebral artery. With reference to FIG. 11B,thrombi can also be located at two vessels (i.e. bi-vessels) as twoseparate clots in similar vessels. With reference to FIGS. 11C and 11D,thrombi can also be located at multi-vessels as one clot that is withinmultiple vessels or as multiple clots that are within multiple vessels.Vessels with such clots can be located, for example, at the intracranialinternal carotid, anterior cerebral and middle cerebral arteries, andbasilar artery and both posterior and cerebral arteries.

Referring to FIG. 12, the medical device 100 can be used in a systemwith a balloon guide catheter 164, with a syringe 166 for expanding aballoon 168, a syringe 170 for aspiration, or both. Aspirationassistance can enable flow reversal through the expandable member 102and thrombus 162. Inflation of the balloon 168 can impede or preventflow proximally through the vessel from the balloon 168 towards theexpandable member 102. As part of the retrieval procedure, continuousaspiration can be employed through the balloon guide catheter 164, withvigorous aspiration when the expandable member 102 is near a distal tipof the balloon guide catheter. The aspiration with flow reversal canhelp allow the distal vasculature to continue to have blood perfusingthrough the vessels during the retrieval process, and can inhibit thepossibility of distal emboli. There can be an advantage to having bloodflow across the expandable member 102 and thrombus 162 with thepotential of natural lysing of blood and increased surface area forthrombus dissolving medicines, if they are provided. The aspiration withflow reversal can also assist in the thrombus retrieval process byaiding in the removal of the thrombus 162. The flow can be directedtowards a lumen of the balloon guide catheter 164 due to the aspiration.The expandable member 102 and thrombus 162 can thus be assisted by theflow to enter the lumen of the balloon guide catheter 164. In someembodiments, if withdrawal into the balloon guide catheter 164 isdifficult for any reason during aspiration, the balloon 168 can bedeflated, and the balloon guide catheter 164, catheter 107, andexpandable member 102 can be withdrawn simultaneously while maintainingaspiration.

A technique for engaging and removing a thrombus 162 and restrictingdownstream travel of secondary emboli during thrombus retrieval will nowbe discussed with reference to FIGS. 13-22. This technique can beperformed with any of the embodiments of the medical device 100 andexpandable member 102 disclosed herein, including any of the expandablemembers 102 of FIG. 2, 8, 9 or 10. Referring to FIG. 13, the medicaldevice 100 may be inserted into an anatomical vessel 172 by firstinserting a guide wire 174 into the anatomical vessel 172. The guidewire 174 is advanced through a guide catheter 164, which optionallyincludes a balloon near the guide catheter's distal end, and a catheter107 to the treatment site, adjacent the thrombus 162. Referring to FIG.14, the guide wire 174 is advanced distally through the thrombus 162.Once in position, the catheter 107 is advanced over the guide wire 174,through a distal end of the guide catheter, into the anatomical vessel172. Referring to FIG. 15, the catheter 107 is advanced distally throughthe thrombus 162. The guide wire 174 is then withdrawn proximally.

Referring to FIG. 16, the medical device 100 is advanced through thecatheter 107 such that the distal portion 120 of the medical device 100is disposed distal of the thrombus 162 in the anatomical vessel 172. Themedical device 100 is advanced through the catheter 107 by themanipulation member 104 coupled to the proximal end of the expandablemember 102. The catheter 107 compresses the expandable member 102 andthus, maintains the expandable member 102 in a compressed,volume-reduced configuration as the expandable member 102 is advanced tothe treatment site.

Referring to FIGS. 17 and 18, the catheter 107 is withdrawn proximallyrelative to the expandable member 102 to expose the expandable member102. If the expandable member is self-expanding, retraction of thecatheter 107 can permit the expandable member 102 to expand. The frame108 expands against a length of the thrombus 162 and engages thethrombus 162. As discussed above, the frame 108 is designed to engageand remove thrombi that are both generally soft, or malleable, orgenerally hard, or callous. A period of time can be allowed to pass toallow blood to reperfuse the downstream area, the expandable member 102to penetrate the thrombus 162, or both.

Referring to FIGS. 19 and 20, the expandable member 102 is withdrawnproximally, along with the thrombus 162. Applying a proximally directedforce to a proximal end of the frame 108 can collapse a distal end ofthe frame 108, prior to withdrawal of the intervention member into theguide catheter 164. The distal end of the frame 108 can collapse to atleast substantially the same extent, and optionally more than, a portionof the frame proximal of the distal end as discussed above.

Referring to FIGS. 12, 20, and 21, in embodiments wherein the guidecatheter 164 comprises a balloon 168, the balloon optionally can beinflated to occlude flow during retraction of the thrombus 162 towardthe guide catheter. In some embodiments, an aspiration syringe 170 canbe attached to the guide catheter 164, and aspiration can be applied toaid thrombus retrieval.

Referring to FIG. 21, the expandable member 102 is withdrawn proximallyto the guide catheter 164. The guide catheter 164 causes the frame 108to collapse, with the thrombus 162 engaged therein. The thrombus 162 isthus retrieved and removed from the anatomical vessel 172. Referring toFIG. 22, if retrieval of the expandable member 102 is determined to beundesirable, e.g., to avoid damaging the vessel 172, and the expandablemember 102 is detachably connected to the manipulation member 104, theexpandable member can be detached from the manipulation member 104 andcan remain in the vessel 172.

Additionally, while the expandable member 102 described above has beendescribed in the context of use during a blood flow restorationprocedure, the expandable member 102 can also, or alternatively, be usedas an implantable member (e.g. stent). For example, the expandablemember 102 can be released through the connection 106 at a stenosis,aneurysm, or other appropriate location in a vessel. The expandablemember 102 can expand and engage a vessel wall so as to hold the vesselwall open and/or act as an occluding member. While the filamentthicknesses, widths, cell sizes, and forces described above can beoptimized for an expandable member 102 for flow restoration, thesevalues can also be optimized for an expandable member 102 for use as animplantable member. In some embodiments the same values can be used forboth flow restoration and use as an implantable member.

Further details regarding expandable members, the manufacture ofexpandable members, and use of expandable members are disclosed in U.S.Pat. No. 7,300,458, entitled Medical Implant Having a Curable MatrixStructure, issued Nov. 27, 2007; U.S. Patent Application Publication No.2011/0060212, entitled Methods and Apparatus for Flow Restoration,published on Mar. 10, 2011; U.S. Patent Application Publication No.2012/0083868, entitled Methods and Apparatuses for Flow Restoration andImplanting Members in the Human Body, published on Apr. 5, 2012; U.S.Patent Application Publication No. 2011/0160763, entitled Blood FlowRestoration in Thrombus Management Methods, published on Jun. 30, 2011;U.S. patent application Ser. No. 13/834,945, entitled Connection of anEndovascular Intervention Device to a Manipulation Member, filed on Mar.15, 2013, published as ______ on ______; and U.S. patent applicationSer. No. 13/835,130, entitled Connection of a Manipulation Member,Including a Bend without Substantial Surface Cracks, to an EndovascularIntervention Device, filed on Mar. 15, 2013, published as ______ on______; the entirety of each of which is hereby incorporated byreference herein.

The foregoing description is provided to enable a person skilled in theart to practice the various configurations described herein. While thesubject technology has been particularly described with reference to thevarious figures and configurations, it should be understood that theseare for illustration purposes only and should not be taken as limitingthe scope of the subject technology.

There may be many other ways to implement the subject technology.Various functions and elements described herein may be partitioneddifferently from those shown without departing from the scope of thesubject technology. Various modifications to these configurations willbe readily apparent to those skilled in the art, and generic principlesdefined herein may be applied to other configurations. Thus, manychanges and modifications may be made to the subject technology, by onehaving ordinary skill in the art, without departing from the scope ofthe subject technology.

It is understood that the specific order or hierarchy of steps in theprocesses disclosed is an illustration of exemplary approaches. Basedupon design preferences, it is understood that the specific order orhierarchy of steps in the processes may be rearranged. Some of the stepsmay be performed simultaneously. The accompanying method claims presentelements of the various steps in a sample order, and are not meant to belimited to the specific order or hierarchy presented.

As used herein, the phrase “at least one of” preceding a series ofitems, with the term “and” or “or” to separate any of the items,modifies the list as a whole, rather than each member of the list (i.e.,each item). The phrase “at least one of” does not require selection ofat least one of each item listed; rather, the phrase allows a meaningthat includes at least one of any one of the items, and/or at least oneof any combination of the items, and/or at least one of each of theitems. By way of example, the phrases “at least one of A, B, and C” or“at least one of A, B, or C” each refer to only A, only B, or only C;any combination of A, B, and C; and/or at least one of each of A, B, andC.

A phrase such as “an aspect” does not imply that such aspect isessential to the subject technology or that such aspect applies to allconfigurations of the subject technology. A disclosure relating to anaspect may apply to all configurations, or one or more configurations.An aspect may provide one or more examples of the disclosure. A phrasesuch as “an aspect” may refer to one or more aspects and vice versa. Aphrase such as “an embodiment” does not imply that such embodiment isessential to the subject technology or that such embodiment applies toall configurations of the subject technology. A disclosure relating toan embodiment may apply to all embodiments, or one or more embodiments.An embodiment may provide one or more examples of the disclosure. Aphrase such “an embodiment” may refer to one or more embodiments andvice versa. A phrase such as “a configuration” does not imply that suchconfiguration is essential to the subject technology or that suchconfiguration applies to all configurations of the subject technology. Adisclosure relating to a configuration may apply to all configurations,or one or more configurations. A configuration may provide one or moreexamples of the disclosure. A phrase such as “a configuration” may referto one or more configurations and vice versa.

Terms such as “top,” “bottom,” “front,” “rear” and the like as used inthis disclosure should be understood as referring to an arbitrary frameof reference, rather than to the ordinary gravitational frame ofreference. Thus, a top surface, a bottom surface, a front surface, and arear surface may extend upwardly, downwardly, diagonally, orhorizontally in a gravitational frame of reference.

Furthermore, to the extent that the term “include,” “have,” or the likeis used in the description or the claims, such term is intended to beinclusive in a manner similar to the term “comprise” as “comprise” isinterpreted when employed as a transitional word in a claim.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any embodiment described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments.

A reference to an element in the singular is not intended to mean “oneand only one” unless specifically stated, but rather “one or more.”Pronouns in the masculine (e.g., his) include the feminine and neutergender (e.g., her and its) and vice versa. The term “some” refers to oneor more. Underlined and/or italicized headings and subheadings are usedfor convenience only, do not limit the subject technology, and are notreferred to in connection with the interpretation of the description ofthe subject technology. All structural and functional equivalents to theelements of the various configurations described throughout thisdisclosure that are known or later come to be known to those of ordinaryskill in the art are expressly incorporated herein by reference andintended to be encompassed by the subject technology. Moreover, nothingdisclosed herein is intended to be dedicated to the public regardless ofwhether such disclosure is explicitly recited in the above description.

While certain aspects and embodiments of the subject technology havebeen described, these have been presented by way of example only, andare not intended to limit the scope of the subject technology. Indeed,the novel methods and systems described herein may be embodied in avariety of other forms without departing from the spirit thereof. Theaccompanying claims and their equivalents are intended to cover suchforms or modifications as would fall within the scope and spirit of thesubject technology.

What is claimed is:
 1. A medical device configured to perform anendovascular therapy, the device comprising: an elongate manipulationmember comprising a distal end portion; and an intervention membercomprising a proximal end portion and a mesh, the proximal end portionbeing coupled with the distal end portion of the elongate manipulationmember, the mesh having a proximal mesh end, a distal mesh end, and amesh length from the proximal end to the distal end, the mesh having aplurality of cells and being compressible to a collapsed configurationfor delivery to an endovascular treatment site through a catheter andbeing self-expandable from the collapsed configuration to an expandedconfiguration, and wherein at least a portion of the mesh, from a firstlocation to a second location along the mesh, is configured such that anamount of cell deformation in response to longitudinally directedtensile forces decreases by less than 5% or increases in a distaldirection along the portion of the mesh, the first and second locationsbeing longitudinally separated by a distance that is more than half ofthe mesh length.
 2. The medical device of claim 1, wherein the portionof the mesh, from the first location to the second location along themesh, is configured such that the amount of cell deformation in responseto longitudinally directed tensile forces does not decrease in a distaldirection along the portion of the mesh.
 3. The medical device of claim1, wherein the portion of the mesh, from the first location to thesecond location along the mesh, is configured such that the amount ofcell deformation in response to longitudinally directed tensile forcesincreases in a distal direction along the portion of the mesh.
 4. Themedical device of claim 1, wherein the first and second locations arelongitudinally separated by a distance that is at least two thirds ofthe mesh length.
 5. The medical device of claim 1, wherein the first andsecond locations are longitudinally separated by a distance that is atleast three quarters of the mesh length.
 6. The medical device of claim1, wherein the first and second locations are longitudinally separatedby a distance that is at least 90% of the mesh length.
 7. The medicaldevice of claim 1, wherein the mesh is generally cylindrical in theabsence of external forces.
 8. A medical device configured to perform anendovascular therapy, the device comprising: an elongate manipulationmember comprising a distal end portion; and an intervention membercomprising a proximal end portion and a plurality of cells forming amesh, the proximal end portion being coupled with the distal end portionof the elongate manipulation member, the mesh having a proximal meshend, a distal mesh end, and a mesh length from the proximal end to thedistal end, the mesh being compressible to a collapsed configuration fordelivery to an endovascular treatment site through a catheter and beingself-expandable from the collapsed configuration to an expandedconfiguration, and wherein, from a first location to a second locationalong the mesh, each cell distally adjacent to another cell, in alongitudinal row of cells, has a larger interior bounded area than hasthe another cell, the first and second locations being longitudinallyseparated by a distance that is more than half of the mesh length. 9.The medical device of claim 8, wherein the first and second locationsare longitudinally separated by a distance that is at least two thirdsof the mesh length.
 10. The medical device of claim 8, wherein the firstand second locations are longitudinally separated by a distance that isat least three quarters of the mesh length.
 11. The medical device ofclaim 8, wherein the first and second locations are longitudinallyseparated by a distance that is at least 90% of the mesh length.
 12. Themedical device of claim 8, wherein the longitudinal row of cellscomprises at least three cells.
 13. The medical device of claim 8,wherein the first location is at the proximal mesh end.
 14. The medicaldevice of claim 8, wherein the first location is distal to aproximal-most cell.
 15. The medical device of claim 8, wherein thesecond location is at the distal mesh end.
 16. The medical device ofclaim 8, wherein the mesh is cylindrical in the absence of externalforces.
 17. The medical device of claim 8, wherein the elongatemanipulation member has a length between a proximal end and the distalend that is sufficient to permit manipulation of the intervention memberwithin the cerebral vasculature of a patient's body from a locationoutside the body.
 18. The medical device of claim 8, wherein the mesh isformed by laser cutting one of a tube or a sheet.
 19. The medical deviceof claim 8, wherein the mesh forms a generally tubular structure. 20.The medical device of claim 8, wherein the mesh further comprises afirst lateral edge extending between the proximal mesh end and thedistal mesh end, and a second lateral edge opposite the first lateraledge, the second lateral edge extending between the proximal mesh endand the distal mesh end; wherein the first and second lateral edges areoverlapped in a coiled configuration about the longitudinal axis whenthe mesh is in the collapsed configuration.
 21. The medical device ofclaim 8, wherein the tube has an open proximal end and an open distalend.
 22. A medical device configured to perform an endovascular therapy,the device comprising: an elongate manipulation member comprising adistal end portion; and an intervention member comprising a proximal endportion and a plurality of cells forming a mesh, the proximal endportion being coupled with the distal end portion of the elongatemanipulation member, the mesh having a proximal mesh end, a distal meshend, and a mesh length from the proximal end to the distal end, the meshbeing compressible to a collapsed configuration for delivery to anendovascular treatment site through a catheter and being self-expandablefrom the collapsed configuration to an expanded configuration, andwherein, in a longitudinal row of at least three cells, each celldistally adjacent to another cell has a larger proximal inscribed strutangle between first and second struts (i) bounding a proximal portion ofthe cell and (ii) diverging in a distal direction, than has the anothercell.
 23. The medical device of claim 22, wherein the first and secondstruts comprises a straight portion and a curved portion, and theinscribed strut angle is measured between the straight portions of thefirst and second struts.
 24. The medical device of claim 22, wherein theinscribe strut angle is measured between straight reference lines thatjoin strut intersection points at each end of the first and secondstruts.
 25. The medical device of claim 22, wherein, for each cell, thefirst strut has a length equal to that of the second strut.
 26. Themedical device of claim 22, wherein the first struts of all cellsbetween the first and second locations have the substantially equallengths.
 27. The medical device of claim 22, wherein the longitudinalrow extends from a first location to a second location along the mesh,the first and second locations being longitudinally separated by adistance that is more than half of the mesh length.
 28. The medicaldevice of claim 27, wherein the first and second locations arelongitudinally separated by a distance that is at least two thirds ofthe mesh length.
 29. The medical device of claim 27, wherein the firstand second locations are longitudinally separated by a distance that isat least three quarters of the mesh length.
 30. The medical device ofclaim 27, wherein the first and second locations are longitudinallyseparated by a distance that is at least 90% of the mesh length.
 31. Themedical device of claim 22, wherein the mesh is cylindrical in theabsence of external forces.